Method for selective etching of antireflective coatings

Abstract

The present invention relates to the fabrication of integrated circuit devices, and more particularly, to a method of etching inorganic antireflective layers without etching excessive amounts of an underlying oxide.

What is claimed as new and desired to be protected by Letters Patent of the United States is:  
     
       1. A method of etching an inorganic antireflective coating in contact with an oxide, said method comprising: 
       applying an etchant to said inorganic antireflective coating, said etchant being characterized in that it etches said inorganic antireflective coating at a rate greater than said oxide;  
       wherein said etchant comprises an oxidizing agent and TMAH tetramethyl ammonium hydroxide).  
     
     
       2. A method of etching as set forth in claim  1 , wherein said etchant comprises about 1 part TMAH (25 wt. % tetramethyl ammonium hydroxide and 75 wt. % aqueous solution) and between about 6 and 7 parts of aqueous solution. 
     
     
       3. A method of forming a semiconductor device, comprising: 
       forming an inorganic antireflective layer over an oxide layer;  
       etching a portion of said inorganic antireflective layer and an underlying portion of said oxide layer, wherein said oxide layer is etched in such amounts so that no portion of said inorganic antireflective layer overhangs said oxide layer; wherein said etchant comprises TMAH (tetramethylammonium hydroxide).  
     
     
       4. The method of claim  3 , wherein said etchant comprises a fluorine-containing compound in an aqueous solution. 
     
     
       5. The method of claim  3 , wherein said etchant comprises about 10-40 wt. % of a fluorine-containing compound in an aqueous solution. 
     
     
       6. The method of claim  3 , wherein said etchant comprises about 35-40 wt. % NH 4 F and about 0.9-5.0 wt. % H 3 PO 4 in an aqueous solution. 
     
     
       7. The method of claim  3 , wherein said etchant further comprises an oxidizing agent. 
     
     
       8. The method of claim  7 , wherein said oxidizing agent is selected from the group consisting of O 3  and H 2 O 2 . 
     
     
       9. The method of claim  7 , wherein said etchant comprises about one part by weight hydrogen peroxide (H 2 O 2 ), and between 30 and 300 parts by weight of a mixture of about 39.2-39.9 wt. % ammonium fluoride, and about 0.9 wt. % phosphoric acid in an aqueous solution. 
     
     
       10. The method of claim  7 , wherein said etchant comprises TMAH (tetramethyl ammonium hydroxide). 
     
     
       11. The method of claim  10 , wherein said etchant comprises about 1 part TMAH (25 wt. % tetramethyl ammonium hydroxide and 75 wt. % aqueous solution) and between about 6 and 7 parts of aqueous solution. 
     
     
       12. The method of claim  3 , wherein said etchant has a pH greater than 11. 
     
     
       13. The method of claim  12 , wherein said etchant has a pH less than 14. 
     
     
       14. The method of claim  13 , wherein said etchant comprises NH 4 OH. 
     
     
       15. A method of fabricating an integrated circuit, said method comprising: 
       providing an insulating layer over semiconductor device structures on a semiconductor substrate;  
       providing an oxide layer over said insulating layer;  
       providing an antireflective layer over said oxide layer;  
       providing a layer of photoresist over said antireflective layer;  
       patterning said photoresist layer; and  
       etching a portion of said antireflective layer and an underlying portion of said oxide layer, wherein said oxide layer is etched in such amounts so that no portion of said antireflective layer overhangs said oxide layer; wherein said etchant comprises TMAH (tetramethylammonium hydroxide).  
     
     
       16. The method of claim  15 , wherein said etchant comprises a fluorine-containing compound. 
     
     
       17. The method of claim  16 , wherein said etchant comprises about 10-40 wt. % of a fluorine-containing compound in an aqueous solution. 
     
     
       18. The method of claim  17 , wherein said etchant comprises about 35-40 wt. % NH 4 F and about 0.9-5.0 wt. % H 3 PO 4 in an aqueous solution. 
     
     
       19. The method of claim  18 , wherein said oxide layer is selected from the group consisting of borophosphosilic glass (BPSG), phosphosilicate glass (PSG), and silicon dioxide. 
     
     
       20. The method of claim  15 , wherein said etchant comprises an oxidizing agent. 
     
     
       21. The method of claim  20 , wherein said oxidizing agent is selected from the group consisting of O 3  and H 2 O 2 . 
     
     
       22. The method of claim  21 , wherein said etchant comprises about one part by weight of hydrogen peroxide (H 2 O 2 ), and between 30 and 300 parts by weight of a mixture about 39.2-39.9 wt. % ammonium fluoride, and about 0.9 wt. % phosphoric acid in an aqueous solution. 
     
     
       23. The method of claim  22 , wherein said oxide layer is selected from the group consisting of borophosphosilic glass (BPSG), phosphosilicate glass (PSG), and silicon dioxide. 
     
     
       24. The method of claim  21 , wherein said etchant comprises about 1 part TMAH (25 wt. % tetramethyl ammonium hydroxide and 75 wt. % aqueous solution) and between about 6 and 7 parts of aqueous solution. 
     
     
       25. The method of claim  24 , wherein said oxide layer is selected from the group consisting of borophosphosilic glass (BPSG), phosphosilicate glass (PSG), and silicon dioxide. 
     
     
       26. The method of claim  15 , wherein said etchant has a pH greater than 11. 
     
     
       27. The method of claim  26 , wherein said etchant has a pH less than 14. 
     
     
       28. The method of claim  27 , wherein said etchant comprises NH 4 OH. 
     
     
       29. A method of fabricating an integrated circuit, said method comprising: 
       providing an insulating layer over semiconductor device structures on a semiconductor substrate;  
       providing an oxide layer over said insulating layer;  
       providing an antireflective layer over said oxide layer;  
       providing a layer of photoresist over said antireflective layer;  
       patterning said photoresist layer;  
       applying an etchant to said antireflective layer wherein said antireflective layer is etched at a rate exceeding the rate of said oxide layer; wherein said etchant comprises TMAH (tetramethylammonium hydroxide).  
     
     
       30. A method of fabricating an integrated circuit as set forth in claim  29  wherein said etchant comprises a fluorine-containing compound. 
     
     
       31. A method of fabricating an integrated circuit as set forth in claim  30  wherein said etchant comprises about 10-40 wt. % of a fluorine-containing compound in an aqueous solution. 
     
     
       32. A method of fabricating an integrated circuit as set forth in claim  31  wherein said etchant comprises about 35-40 wt. % NH 4 F and about 0.9-5.0 wt. % H 3 PO 4 in an aqueous solution. 
     
     
       33. A method of fabricating an integrated circuit as set forth in claim  32  wherein said oxide layer is selected from the group consisting of borophosphosilic glass (BPSG), phosphosilicate glass (PSG), and silicon dioxide. 
     
     
       34. A method of fabricating an integrated circuit as set forth in claim  29  wherein said etchant comprises an oxidizing agent. 
     
     
       35. A method of fabricating an integrated circuit as set forth in claim  34  wherein said oxidizing agent is selected from the group consisting of O 3  and H 2 O 2 . 
     
     
       36. A method of fabricating an integrated circuit as set forth in claim  35  wherein said etchant comprises about one part by weight of hydrogen peroxide (H 2 O 2 ), and between 30 and 300 parts by weight of a mixture about 39.2-39.9 wt. % ammonium fluoride, and about 0.9 wt. % phosphoric acid in an aqueous solution. 
     
     
       37. A method of fabricating an integrated circuit as set forth in claim  36  wherein said oxide layer is selected from the group consisting of borophosphosilic glass (BPSG), phosphosilicate glass (PSG), and silicon dioxide. 
     
     
       38. A method of fabricating an integrated circuit as set forth in claim  35  wherein said etchant comprises about 1 part TMAH (25 wt. % tetramethyl ammonium hydroxide and 75 wt. % aqueous solution) and between about 6 and 7 parts of aqueous solution. 
     
     
       39. A method of fabricating an integrated circuit as set forth in claim  38  wherein said oxide layer is selected from the group consisting of borophosphosilic glass (BPSG), phosphosilicate glass (PSG), and silicon dioxide. 
     
     
       40. A method of fabricating an integrated circuit as set forth in claim  39  wherein said etchant has a pH greater than 11. 
     
     
       41. A method of fabricating an integrated circuit as set forth in claim  40  wherein said etchant has a pH less than 14. 
     
     
       42. A method of fabricating an integrated circuit as set forth in claim  41  wherein said etchant comprises NH 4 OH. 
     
     
       43. A method of fabricating an integrated circuit as set forth in claim  42  wherein said oxide layer is selected from the group consisting of borophosphosilic glass (BPSG), phosphosilicate glass (PSG), and silicon dioxide.